scholarly journals First validation of GOME-2/MetOp Absorbing Aerosol Height using EARLINET lidar observations

2020 ◽  
Author(s):  
Konstantinos Michailidis ◽  
Maria-Elissavet Koukouli ◽  
Nikolaos Siomos ◽  
Dimitrios Balis ◽  
Olaf Tuinder ◽  
...  
Keyword(s):  
Saharan Dust ◽  
Aerosol Layer ◽  
Pixel Size ◽  
Geometrical Features ◽  
Depth Analysis ◽  
Satellite Sensors ◽  
The Mean ◽  
The Difference ◽  
Ground Based Lidar ◽  
Lidar Observations

Abstract. The aim of this study is to investigate the potential of GOME-2 instruments on board the MetOpA, MetOpB and MetOpC platforms, to deliver accurate geometrical features of lofted aerosol layers. For this purpose, we use archived ground-based lidar data from lidar stations available fromEuropean Aerosol Research Lidar Network (EARLINET) database. The data are post-processed with the wavelet covariance transform (WCT) method in order to extract geometrical features such as the Planetary Boundary Layer, PBL, height and the cloud boundaries. To obtain a significant number of collocated and coincident GOME-2 – EARLINET cases for the period between January 2007 and September 2019, fourteenlidar stations, distributed over different European latitudes, contributed to this validation. For the 172 carefully screened collocations, the mean bias was found to be −0.18 ± 1.68 km, with a near Gaussian distribution. On a station-basis, and with a couple of exceptions where very few collocations were found, their mean biases fall in the ± 1 km range with an associated standard deviation between 0.5 and 1.5 km. Considering the differences, mainly due to the temporal collocation and the difference between the satellite pixel size and the point view of the ground-based observations, these results are quite promising and demonstrating that stable and extended aerosol layers as captured by the satellite sensors, are verified by the ground-based data. We further present an in-depth analysis of a strong and long-lasting Saharan dust intrusion over the Iberian Peninsula. We show that for, this well-developed and spatially well-spread aerosol layer, most GOME-2 retrievals fall within 1 km of the exactly temporally collocated lidar observation for the entire range of 0 to 150 km radii. This finding further testifies to the capabilities of the MetOp-born instruments to sense the atmospheric aerosol layer height.

scholarly journals First validation of GOME-2/MetOp absorbing aerosol height using EARLINET lidar observations

2021 ◽  
Vol 21 (4) ◽  
pp. 3193-3213
Author(s):  
Konstantinos Michailidis ◽  
Maria-Elissavet Koukouli ◽  
Nikolaos Siomos ◽  
Dimitris Balis ◽  
Olaf Tuinder ◽  
...  
Keyword(s):  
Saharan Dust ◽  
Aerosol Layer ◽  
Pixel Size ◽  
Geometrical Features ◽  
Depth Analysis ◽  
Satellite Sensors ◽  
The Mean ◽  
The Difference ◽  
Ground Based Lidar ◽  
Lidar Observations

Abstract. The aim of this study is to investigate the potential of the Global Ozone Monitoring Experiment-2 (GOME-2) instruments, aboard the Meteorological Operational (MetOp)-A, MetOp-B and MetOp-C satellite programme platforms, to deliver accurate geometrical features of lofted aerosol layers. For this purpose, we use archived ground-based lidar data from stations available from the European Aerosol Research Lidar Network (EARLINET) database. The data are post-processed using the wavelet covariance transform (WCT) method in order to extract geometrical features such as the planetary boundary layer (PBL) height and the cloud boundaries. To obtain a significant number of collocated and coincident GOME-2 – EARLINET cases for the period between January 2007 and September 2019, 13 lidar stations, distributed over different European latitudes, contributed to this validation. For the 172 carefully screened collocations, the mean bias was found to be −0.18 ± 1.68 km, with a near-Gaussian distribution. On a station basis, and with a couple of exceptions where very few collocations were found, their mean biases fall in the ± 1 km range with an associated standard deviation between 0.5 and 1.5 km. Considering the differences, mainly due to the temporal collocation and the difference, between the satellite pixel size and the point view of the ground-based observations, these results can be quite promising and demonstrate that stable and extended aerosol layers as captured by the satellite sensors are verified by the ground-based data. We further present an in-depth analysis of a strong and long-lasting Saharan dust intrusion over the Iberian Peninsula. We show that, for this well-developed and spatially well-spread aerosol layer, most GOME-2 retrievals fall within 1 km of the exact temporally collocated lidar observation for the entire range of 0 to 150 km radii. This finding further testifies for the capabilities of the MetOp-borne instruments to sense the atmospheric aerosol layer heights.

scholarly journals Spatial distribution analysis of the OMI aerosol layer height: a pixel-by-pixel comparison to CALIOP observations

2018 ◽  
Vol 11 (4) ◽  
pp. 2257-2277 ◽  
Author(s):  
Julien Chimot ◽  
J. Pepijn Veefkind ◽  
Tim Vlemmix ◽  
Pieternel F. Levelt
Keyword(s):  
Air Quality ◽  
Eastern China ◽  
Weighted Average ◽  
Saharan Dust ◽  
Trace Gas ◽  
High Temporal Resolution ◽  
Aerosol Layer ◽  
Distribution Analysis ◽  
Layer Height ◽  
Satellite Sensors

Abstract. A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation, and air quality research studies but also for correcting scattered radiation induced by aerosols in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH) was retrieved from the OMI 477 nm O2−O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in eastern China shows consistent spatial patterns with an uncertainty in the range of 462–648 m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South America and Russia from OMI visible measurements. A Saharan dust outbreak over sea is finally discussed. Complementary detailed analyses show that the assumed aerosol properties in the forward modelling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477 nm O2−O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals.

scholarly journals Australian Lidar Measurements of Aerosol Layers Associated with the 2015 Calbuco Eruption

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 124
Author(s):  
Andrew R. Klekociuk ◽  
David J. Ottaway ◽  
Andrew D. MacKinnon ◽  
Iain M. Reid ◽  
Liam V. Twigger ◽  
...  
Keyword(s):  
Vertical Motion ◽  
Stratospheric Aerosol ◽  
Spatial Inhomogeneity ◽  
Volcanic Plume ◽  
Orthogonal Polarization ◽  
Aerosol Layer ◽  
Lidar Measurements ◽  
The Mean ◽  
Volcanic Aerosols ◽  
Ground Based Lidar

The Calbuco volcano in southern Chile (41.3° S, 72.6° W) underwent three separate eruptions on 22–23 April 2015. Following the eruptions, distinct layers of enhanced lidar backscatter at 532 nm were observed in the lower stratosphere above Buckland Park, South Australia (34.6° S, 138.5° E), and Kingston, Tasmania (43.0° S, 147.3° E), during a small set of observations in April–May 2015. Using atmospheric trajectory modelling and measurements from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) space-borne lidar and the Ozone Mapping Profiler Suite (OMPS) instrument on the Suomi National Polar-orbiting Partnership (NPP) satellite, we show that these layers were associated with the Calbuco eruptions. Buckland Park measurements on 30 April and 3 May detected discrete aerosol layers at and slightly above the tropopause, where the relative humidity was well below saturation. Stratospheric aerosol layers likely associated with the eruptions were observed at Kingston on 17 and 22 May in narrow discrete layers accompanied by weaker and more vertically extended backscatter. The measurements on 22 May provided a mean value of the particle linear depolarisation ratio within the main observed volcanic aerosol layer of 18.0 ± 3.0%, which was consistent with contemporaneous CALIOP measurements. The depolarisation measurements indicated that this layer consisted of a filament dominated by ash backscatter residing above a main region having likely more sulfate backscatter. Layer-average optical depths were estimated from the measurements. The mean lidar ratio for the volcanic aerosols on 22 May of 86 ± 37 sr is consistent with but generally higher than the mean for ground-based measurements for other volcanic events. The inferred optical depth for the main volcanic layer on 17 May was consistent with a value obtained from OMPS measurements, but a large difference on 22 May likely reflected the spatial inhomogeneity of the volcanic plume. Short-lived enhancements of backscatter near the tropopause of 17 May likely represented the formation cirrus that was aided by the presence of associated volcanic aerosols. We also provide evidence that gravity waves potentially influenced the layers, particularly in regard to the vertical motion observed in the strong layer on 22 May. Overall, these observations provide additional information on the dispersal and characteristics of the Calbuco aerosol plumes at higher southern latitudes than previously reported for ground-based lidar measurements.

scholarly journals Absorption of aerosols above clouds from POLDER/PARASOL measurements and estimation of their Direct Radiative Effect

2014 ◽  
Vol 14 (18) ◽  
pp. 25533-25579 ◽  
Author(s):  
F. Peers ◽  
F. Waquet ◽  
C. Cornet ◽  
P. Dubuisson ◽  
F. Ducos ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Single Scattering ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Radiative Effect ◽  
East Atlantic ◽  
Aerosol Absorption ◽  
Cloud Optical Thickness ◽  
The Mean ◽  
Aerosol Properties

Abstract. The albedo of clouds and the aerosol absorption are key parameters to evaluate the direct radiative effect of an aerosol layer above clouds. While most of the retrievals of above clouds aerosol characteristics rely on assumptions on the aerosol properties, this study offers a new method to evaluate aerosol and cloud optical properties simultaneously (i.e. aerosol and cloud optical thickness, aerosol single scattering albedo and angström exponent). It is based on multi-angle total and polarized radiances both provided by the A-train satellite instrument POLDER – Polarization and Directionality of Earth Reflectances. The sensitivities brought by each kind of measurements are used in a complementary way. Polarization mostly translates scattering processes and is thus used to estimate the scattering aerosol optical thickness and the aerosol size. On the other hand, total radiances, together with the scattering properties of aerosols, are used to evaluate the absorption optical thickness of aerosols and the cloud optical thickness. In addition, a procedure has been developed to process the shortwave direct radiative effect of aerosols above clouds based on exact modeling. Besides the three case studies (i.e. biomass burning aerosols from Africa and Siberia and Saharan dust), both algorithms have been applied on the South East Atlantic Ocean and results have been averaged through August 2006. The mean direct radiative effect is found to be 33.5 W m−2. Finally, the effect of the heterogeneity of clouds has been investigated and reveals that it affects mostly the retrieval of the cloud optical thickness and not much the aerosols properties. The homogenous cloud assumption used in both the properties retrieval and the DRE processing leads to a slight underestimation of the DRE.

scholarly journals Parameterizing the Difference in Cloud Fraction Defined by Area and by Volume as Observed with Radar and Lidar

2005 ◽  
Vol 62 (7) ◽  
pp. 2248-2260 ◽  
Author(s):  
Malcolm E. Brooks ◽  
Robin J. Hogan ◽  
Anthony J. Illingworth
Keyword(s):  
Wind Shear ◽  
General Circulation ◽  
Cloud Cover ◽  
Cloud Fraction ◽  
Vertical Resolution ◽  
Ice Clouds ◽  
Cloud Radar ◽  
The Mean ◽  
The Difference ◽  
Lidar Observations

Abstract Most current general circulation models (GCMs) calculate radiative fluxes through partially cloudy grid boxes by weighting clear and cloudy fluxes by the fractional area of cloud cover (Ca), but most GCM cloud schemes calculate cloud fraction as the volume of the grid box that is filled with cloud (Cυ). In this paper, 1 yr of cloud radar and lidar observations from Chilbolton in southern England, are used to examine this discrepancy. With a vertical resolution of 300 m it is found that, on average, Ca is 20% greater than Cυ, and with a vertical resolution of 1 km, Ca is greater than Cυ by a factor of 2. The difference is around a factor of 2 larger for liquid water clouds than for ice clouds, and also increases with wind shear. Using Ca rather than Cυ, calculated on an operational model grid, increases the mean total cloud cover from 53% to 63%, and so is of similar importance to the cloud overlap assumption. A simple parameterization, Ca = [1 + e(−f )(C−1υ − 1)]−1, is proposed to correct for this underestimate based on the observation that the observed relationship between the mean Ca and Cυ is symmetric about the line Ca = 1 − Cυ. The parameter f is a simple function of the horizontal (H) and vertical (V) grid-box dimensions, where for ice clouds f = 0.0880 V 0.7696 H−0.2254 and for liquid clouds f = 0.1635 V 0.6694 H−0.1882. Implementing this simple parameterization, which excludes the effect of wind shear, on an independent 6-month dataset of cloud radar and lidar observations, accounts for the mean underestimate of Ca for all horizontal and vertical resolutions considered to within 3% of the observed Ca, and reduces the rms error for each individual box from typically 100% to approximately 30%. Small biases remain for both weakly and strongly sheared cases, but this is significantly reduced by incorporating a simple shear dependence in the calculation of the parameter f, which also slightly improves the overall performance of the parameterization for all of the resolutions considered.

scholarly journals Using self organising maps to explore ozone profile validation results – SCIAMACHY limb compared to ground-based lidar observations

2014 ◽  
Vol 7 (4) ◽  
pp. 4373-4406
Author(s):  
J. A. E. van Gijsel ◽  
R. Zurita-Milla ◽  
P. Stammes ◽  
S. Godin-Beekmann ◽  
T. Leblanc ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
A Priori ◽  
Relative Difference ◽  
Full Time ◽  
Self Organizing Map ◽  
Ozone Profile ◽  
The Difference ◽  
Ground Based Lidar ◽  
Lidar Observations

Abstract. Traditional validation of atmospheric profiles is based on the intercomparison of two or more datasets in predefined ranges or classes of a given observational characteristic such as latitude or solar zenith angle. In this study we train a self organizing map (SOM) with a full time series of relative difference profiles of SCIAMACHY limb v5.02 and lidar ozone profiles from seven observation sites. Each individual observation characteristic is then mapped to the obtained SOM to investigate to which degree variation in this characteristic is explanatory for the variation seen in the SOM map. For the studied datasets, altitude-dependent relations for the global dataset were found between the difference profiles and studied variables. From the lowest altitude studied (18 km) ascending, the most influencing factors were found to be longitude, followed by solar zenith angle and latitude, sensor age and again solar zenith angle together with the day of the year at the highest altitudes studied here (up to 45 km). Clustering into three classes showed that there are also some local dependencies, with for instance one cluster having a much stronger correlation with the sensor age (days since launch) between 36 and 42 km. It was shown that the proposed approach provides a powerful tool for the exploring of differences between datasets without being limited to a-priori defined data subsets.

scholarly journals Characteristics of Volcanic Stratospheric Aerosol Layer Observed by CALIOP and Ground Based Lidar at Equatorial Atmosphere Radar Site

2018 ◽  
Vol 176 ◽  
pp. 04003
Author(s):  
Makoto Abo ◽  
Yasukuni Shibata ◽  
Chikao Nagasawa
Keyword(s):  
Dynamic Behavior ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Equatorial Region ◽  
Aerosol Layer ◽  
Low Latitude ◽  
Ground Based Lidar ◽  
Lidar Observations ◽  
Characteristic Dynamic

We investigated the relation between major tropical volcanic eruptions in the equatorial region and the stratospheric aerosol data, which have been collected by the ground based lidar observations at at Equatorial Atmosphere Radar site between 2004 and 2015 and the CALIOP observations in low latitude between 2006 and 2015. We found characteristic dynamic behavior of volcanic stratospheric aerosol layers over equatorial region.

scholarly journals Simultaneous observations of NLCs and MSEs at midlatitudes: implications for formation and advection of ice particles

2018 ◽  
Vol 18 (21) ◽  
pp. 15569-15580 ◽  
Author(s):  
Michael Gerding ◽  
Jochen Zöllner ◽  
Marius Zecha ◽  
Kathrin Baumgarten ◽  
Josef Höffner ◽  
...  
Keyword(s):  
Radar Data ◽  
Data Set ◽  
Vhf Radar ◽  
Ice Cloud ◽  
Ice Particles ◽  
Summer Echoes ◽  
History Of ◽  
The Mean ◽  
Ground Based Lidar ◽  
Lidar Observations

Abstract. We combined ground-based lidar observations of noctilucent clouds (NLCs) with collocated, simultaneous radar observations of mesospheric summer echoes (MSEs) in order to compare ice cloud altitudes at a midlatitude site (Kühlungsborn, Germany, 54∘ N, 12∘ E). Lidar observations are limited to larger particles (>10 nm), while radars are also sensitive to small particles (<10 nm), but require sufficient ionization and turbulence at the ice cloud altitudes. The combined lidar and radar data set thus includes some information on the size distribution within the cloud and through this on the “history” of the cloud. The soundings for this study are carried out by the IAP Rayleigh–Mie–Raman (RMR) lidar and the OSWIN VHF radar. On average, there is no difference between the lower edges (zNLClow and zMSElow). The mean difference of the upper edges zNLCup and zMSEup is ∼500 m, which is much less than expected from observations at higher latitudes. In contrast to high latitudes, the MSEs above our location typically do not reach much higher than the NLCs. In addition to earlier studies from our site, this gives additional evidence for the supposition that clouds containing large enough particles to be observed by lidar are not formed locally but are advected from higher latitudes. During the advection process, the smaller particles in the upper part of the cloud either grow and sediment, or they sublimate. Both processes result in a thinning of the layer. High-altitude MSEs, usually indicating nucleation of ice particles, are rarely observed in conjunction with lidar observations of NLCs at Kühlungsborn.

scholarly journals Spatial distribution analysis of the OMI aerosol layer height: a pixel-by-pixel comparison to CALIOP observations

2017 ◽  
Author(s):  
Julien Chimot ◽  
J. Pepijn Veefkind ◽  
Tim Vlemmix ◽  
Pieternel F. Levelt
Keyword(s):  
Air Quality ◽  
Weighted Average ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Trace Gas ◽  
High Temporal Resolution ◽  
Aerosol Layer ◽  
Distribution Analysis ◽  
Layer Height ◽  
Satellite Sensors

Abstract. A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation and air quality research studies, but also for correcting aerosol radiation effect in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH) was retrieved from the OMI 477 nm O2−O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in east China shows consistent spatial patterns with an uncertainty in the range of 462–648 m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South-America and Russia, and of a Saharan dust outbreak over sea from OMI visible measurements. Complementary detailed analyses show that the assumed aerosol properties in the modeling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477 nm O2−O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals.

scholarly journals Assessing CALIOP-Derived Planetary Boundary Layer Height Using Ground-Based Lidar

2021 ◽  
Vol 13 (8) ◽  
pp. 1496
Author(s):  
Man-Hae Kim ◽  
Huidong Yeo ◽  
Soojin Park ◽  
Do-Hyeon Park ◽  
Ali Omar ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Radiosonde Data ◽  
Orthogonal Polarization ◽  
Aerosol Layer ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The Difference ◽  
Ground Based Lidar

Coincident profiles from the space-borne and ground-based lidar measurements provide a unique opportunity to estimate the planetary boundary layer height (PBLH). In this study, PBLHs derived from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) were assessed by comparing them with those obtained from the ground-based lidar at Seoul National University (SNU) in Korea for both day and night from 2006 to 2019, and sounding data. CALIOP-derived PBLHs using wavelet covariance transform (WCT) are generally higher than those derived from the SNU lidar for both day and night. The difference in PBLH tends to increase as the signal-to-noise ratio for CALIOP decreases. The difference also increases as aerosol optical depth increases, implying that the PBLH estimated from CALIOP could be higher than that determined from the SNU lidar because of the signal attenuation within the aerosol layer under optically thick aerosol layer conditions. The higher PBLH for CALIOP in this study is mainly attributed to multiple aerosol layers. After eliminating multilayer cases, the PBLHs estimated from both the lidars showed significantly improved agreement: a mean difference of 0.09 km (R = 0.81) for daytime and 0.25 km (R = 0.51) for nighttime. The results from this study suggest that PBL detection using CALIOP is reliable for daytime if multilayer cases are removed. For nighttime, PBLHs derived from the SNU lidar and CALIOP showed a relatively large difference in frequency distribution compared with sounding data. It suggests that further investigations are needed for nighttime PBLHs, such as investigations about discriminating the residual layer and the difference between lidar-derived PBLH based on the aerosol layer and thermally derived PBLH from radiosonde data for the stable boundary layer during the nighttime.

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